This invention relates to electrical limit switches of the type wherein an actuator lever is attached to a rotatable shaft journaled in a housing. Deflection of the distal end of the lever effects rotation of the shaft which in turn effects operation of a snap action switch within the housing. More particularly, this invention relates to improved means for mounting an actuator lever to a rotatable shaft of an electrical limit switch.
Limit switch actuator levers are usually die cast of a light weight material such as aluminum or the like. A hole is provided in the lever for disposition of the lever over a rotatable shaft of the limit switch. Various means have been provided heretofore for securely attaching the lever to the shaft such as providing a slotted end in the lever and providing a clamping member around that slotted end to clamp the lever to the shaft as shown in U.S. Pat. No. 3,385,129 to E. F. Duncan et al. Another means for attaching an actuator lever to a limit switch rotatable shaft provides a second hole in the lever at right angles to the hole for the shaft wherein the second hole partially intersects the first hole. A screw threaded pin placed in the second hole is provided with a recess in the shank portion thereof which aligns with the hole for the shaft and thereby affords clearance for the limit switch shaft. A nut is turned onto the threaded portion at an exterior surface of the lever to draw the shank of the pin toward the nut when tightened, thereby wedging an edge of the recessed surface against the rotatable shaft to clamp the lever to the shaft as shown in U.S. Pat. Nos. 3,255,641 issued to W. J. Russell and 3,041,888 issued to W. F. Dehn. Still another attachment means is shown in U.S. Pat. No. 3,045,289 issued to G. M. Hipple wherein a cylindrical peg having a flattened surface is inserted within a second opening intersecting the shaft opening of the lever. A transition from the flat surface to the cylindrical shape of the peg provides a wedge against the shaft when a set screw is tightened within a threaded outer end portion of the second opening of the lever. A spring pin is driven through a third hole in the lever to cooperatively engage the flattened surface of the peg to keep the peg properly aligned relative to the opening for the shaft.
The patent to Duncan et al addresses advantages realized by eliminating appendages extending from the mounting end of the lever which could interfere with machinery surfaces to restrict full movement of the lever, and by providing the screw threads in a hard metal member such as a steel bracket or the like. Hipple recognizes a problem with the cylindrical pin wedge such as used in the patents to Russell and Dehn. The cylindrical shape of the pin shank within the cylindrical second hole requires that the screw not only be linearly positioned within the second hole, but also be rotated to cause the recess in the pin to align with the hole for the shaft in order to assemble the lever to the shaft. Hipple provides a flattened end portion of a cylindrical peg and a spring pin driven into a third hole in the lever intersecting the second hole. The peg is rotated to align the flattened end portion with the spring pin and then fully inserted into the second hole whereby the flattened end portion cooperates with the spring pin to maintain the peg rotatably positioned within the lever. This construction has the disadvantage of requiring a third hole in the lever and a spring pin driven into the third hole, thereby requiring additional operations and parts for the assembly of the lever. Hipple also does not provide a hard metal such as steel for the threads engaged by the clamping screw.